Light grids or automation light grids are used as measuring systems for determining object heights and/or object widths. Light grids or automation light grids are furthermore used for the detection of objects in a monitored zone.
An interruption of a light beam in the monitored zone is evaluated in these applications.
If now a more complex evaluation of the monitored area, this means of a two-dimensional region, becomes necessary, then this indicates an evaluation taking place remote from the light grid.
In these cases, the light grid permanently provides information on the individual light barriers and/or light axes having the light beams to an external evaluation unit, for example a PC or a unit similar to a PC, which so-to-say continuously stitches the individual sectional frames in the monitored zone of the light grid to form an image and evaluates them.
Depending on the sampling rate and the number of beams, a large amount of data has to be transmitted to the external evaluation unit and the external evaluation unit has to be configured as very powerful in order to be able to evaluate the constantly accumulating data. A high demand in effort and cost thereby arises with regard to the external evaluation unit.
Furthermore, a data interface of the light grid also has to be configured as powerful in order to provide a large amount of data to the external evaluation unit.
DE 102 01 894 B4 discloses a light grid having additional inputs and an integrated freely programmable logic unit.
DE 103 29 881 A1 discloses a light grid for contour measurement, wherein reference values are stored in the light grid. The reference values are, for example, taught by means of a teaching in at distinctive points.